The destruction of RNA is a process of fundamental biochemical importance, and also has direct bearing on the development of new genomic-based drug strategies. The destruction of RNA is accomplished in this proposal by inorganic catalysts that cleave RNA through transesterification of its phosphodiester backbone. For example, appropriate catalysts are derived from Cu(II)terpyridine, as well as from other complexes of copper, zinc and the lanthanides. Here, the mechanism of RNA cleavage by all of these classes of catalyst will be studied using a new substrate containing a single RNA residue embedded in a DNA polymer. The new substrate is called "embedded RNA", or embRNA. The embRNA substrate maintains the biological relevance of RNA polymers but provides the simplicity and practicality inherent to RNA dimers. EmbRNA furthermore allows highly specific features of RNA-metal binding to be assessed for their importance to the cleavage reaction. These features in clud e charge and hydrophobic effects, remote coordination of metals, and subtle two-metal mechanisms. The work has relevance to development of pharmaceutical reagents to fight viral infections and cancer. The approach is to gain an understanding of the reaction mechanism so that RNA cleavage can be optimized for use in chemotherapy. The mechanistic information gained from this work will feed into separate projects that focus on the sequence-specific cleavage of RNA by ribozyme mimics. Mass spectrometry is used for characterizing these materials.